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8.4.3. Using Yum Variables
You can use and reference the following built-in variables in
yum
commands and in all Yum configuration files (that is, /etc/yum.conf
and all .repo
files in the /etc/yum.repos.d/
directory):
$releasever
- You can use this variable to reference the release version of Red Hat Enterprise Linux. Yum obtains the value of
$releasever
from thedistroverpkg=value
line in the/etc/yum.conf
configuration file. If there is no such line in/etc/yum.conf
, thenyum
infers the correct value by deriving the version number from the redhat-release-server package. The value of$releasever
typically consists of the major release number and the variant of Red Hat Enterprise Linux, for example6Client
, or6Server
. $arch
- You can use this variable to refer to the system's CPU architecture as returned when calling Python's
os.uname()
function. Valid values for$arch
includei686
andx86_64
. $basearch
- You can use
$basearch
to reference the base architecture of the system. For example, i686 machines have a base architecture ofi386
, and AMD64 and Intel 64 machines have a base architecture ofx86_64
. $YUM0-9
- These ten variables are each replaced with the value of any shell environment variables with the same name. If one of these variables is referenced (in
/etc/yum.conf
for example) and a shell environment variable with the same name does not exist, then the configuration file variable is not replaced.
To define a custom variable or to override the value of an existing one, create a file with the same name as the variable (without the “
$
” sign) in the /etc/yum/vars/
directory, and add the desired value on its first line.
For example, repository descriptions often include the operating system name. To define a new variable called
$osname
, create a new file with “Red Hat Enterprise Linux” on the first line and save it as /etc/yum/vars/osname
:
~]# echo "Red Hat Enterprise Linux" > /etc/yum/vars/osname
Instead of “Red Hat Enterprise Linux 6”, you can now use the following in the
.repo
files:
name=$osname $releasever